对畜禽屠宰场主要传播疫病途径以及防控对策的研究

一直以来,对于畜禽疫病防控方面的工作,都是全社会最关注的部分.通过高品质畜禽的供应,将为人们的生活提供有力的基础保障资源,且一旦有不健康的畜禽流入到市场,所产生的影响度将是难以估量的部分.为此,开展畜禽屠宰场疫病防控的工作,将不仅是当下,更加是未来一段时间内,各级相关管理部门,需要主抓与严抓的最重要的工作方面,且只有对...     

弓形虫传播途径的实验研究

弓形虫传播途径的实验研究杨月中，曾丽（云南农业大学动物科技学院）田保平（中国科学院昆明动物研究所）弓形虫可引起人和众多动物的感染。它的传播途径复杂，既可发生垂直的先天感染，又可发生水平的获得感染［１］。人和动物可通过食入受感染猫粪中的成熟卵囊，也可通...     

非洲猪瘟传播途径探讨

非洲猪瘟主要通过直接接触进行传播,也可通过染疫猪、猪肉、食品、车辆、人员、物品、排泄物、饲料间接传播,还可通过软蜱、鸟类、吸血昆虫、猫狗等媒介进行传播。本文通过分析非洲猪瘟的传播途径,提出了针对性的防控措施。     

狂犬病传播途径

狂犬病是由病毒引起的一种人畜共患的急性接触性传染病 ,是危害人及家畜的主要传染病之一 ,发病者几乎 1 0 0 %死亡。病毒主要侵害神经系统 ,临诊特征为狂躁不安 ,意识紊乱 ,兴奋 ,恐水 ,咽肌痉挛 ,最后因局部或全身麻痹而死亡。狂犬病传播途径绝大多数病例是通过患狂犬病动物咬伤而感染的 ,经消化道、抓伤、舔或触摸伤口、母体胎盘、呼吸道等其它非咬伤性的传播途径也可感染。1　咬伤是传播狂犬病的主要途径人和家畜绝大多数病例是通过患狂犬病的动物咬伤而感染的。我国狂犬病患者 (人 )所受的感染方法 ,一般多由狂犬直接咬伤所致 ,如黑龙…     

非洲猪瘟的传播途径与防控

非洲猪瘟是由非洲猪瘟病毒引起的一种急性、烈性传染病。非洲猪瘟疫情的持续暴发严重打击了消费者的消费耐心,极大阻碍了生猪养殖和猪肉制品加工产业的发展,带来了负面影响。本文阐述了非洲猪瘟的病原特点、传播途径及防控措施,以供养猪户参考和借鉴。     

非洲猪瘟的传播途径与防控措施

非洲猪瘟(African Swine Fever,ASF)是由非洲猪瘟病毒(African Swine Fever Virus,ASFV)感染家猪和野猪引起的一种烈性、出血性传染病。以前,该病主要在非洲呈地方性流行,现在已蔓延至欧洲和亚洲,并侵入我国。2018年8月,该病首次在我国被发现,截至目前,农业农村部已报道132起疫情。该病的流行对我国乃至世界养猪业构成巨大威胁,畜产品贸易受阻,造成严重的经济损失。由于目前还没有安全有效的疫苗可用于预防该病,只能靠早监测、早发现进行防控,以求尽快控制或根除该疫病。笔者通过对ASF的流行情况、病原、感染机制、病毒的传播途径、临床症状和病变、诊断和控制措施等方面进行介绍,以期让兽医从业者和养殖者更全面地了解ASF,做到早发现、快速诊断,减少疫病对养殖者和畜牧业造成的损失。     

Dynamics of viral spread in bluetongue virus infected calves

The kinetics of viremia and sites of viral replication in bluetongue virus (BTV) infected calves were characterized by virus isolation, serology and immunofluorescence staining procedures. In addition, the role of the regional lymph node and lymphatics draining inoculated skin in the pathogenesis of BTV infection was determined by analyzing efferent lymph collected from indwelling cannulas. Viremia persisted for 35 to 42 days after inoculation (DAI) and virus co-circulated with neutralizing antibodies for 23 to 26 days. Virus was first isolated from peripheral blood mononuclear (PBM) cells at 3 DAI, after stimulation of PBM cells with interleukin 2 and mitogen. BTV was frequently isolated from erythrocytes, platelets and stimulated PBM cells but never from granulocytes and rarely from plasma during viremia. Virus was consistently isolated from erythrocytes late in the course of veremia. Interruption of efferent lymph flow by cannulation delayed the onset of viremia to 7 DAI. BTV was infrequently isolated from lymph cells, and few fluorescence positive cells were observed after lymph and PBM cells were labelled with a BTV-specific monoclonal antibody. Virus was isolated from spleen by 4 DAI and most tissues by 6 DAI, whereas virus was isolated from bone marrow only at 10 DAI. Virus was not isolated from any tissue after termination of viremia. It is concluded that primary viral replication occurred in the local lymph node and BTV then was transported in low titer to secondary sites of replication via infected lymph and PBM cells. We speculate that virus replication in spleen resulted in release of virus into the circulation and non-selective infection of blood cells which disseminated BTV to other tissues. Virus association with erythrocytes likely was responsible for prolonged viremia, although infected erythrocytes eventually were cleared from the circulation and persistent BTV infection of calves did not occur.     

Assessment of strategies to control BVDV spread in a dairy herd using computer simulation

The efficiency of a test-and-cull programme to control BVDV spread within a dairy herd was assessed using a stochastic model. A single virus introduction by a non-PI dam carrying a PI foetus was simulated in a typical western-France dairy herd. Herd monitoring in test-and-cull programme enabled us to detect virus spread within 1 year after introduction in 87% of the replications. The test-and-cull programme reduced the length of the virus persistence. The extent of infection was moderately reduced.     

Immunohistochemical analysis of pseudorabies virus spread through neurons innervating the eyeball

Pseudorabies virus (PRV) was inoculated intraocularly into BALB/c mice, and the distribution pattern of cells positive for several neurotransmitters and viral antigens in the eyeball, trigeminal nerve ganglia, and superior cervical ganglia was examined immunohistochemically to clarify the neural route of the virus spread. In the eyeball, substance P (SP)- and calcitonin gene-related peptide (CGRP)-positive cells were detected in the ipsilateral iris and ciliary body, neuropeptide tyrosine (NPY)-positive cells were detected in the choloid membrane, and tyrosine hydroxylase (TH)-positive cells were detected in the ipsilateral inner nuclear layer of the retina; all these cells contained viral antigens. In the superior cervical ganglia, viral antigen-positive cells containing TH or NPY were found at bilateral sites. In the trigeminal nerve ganglia, viral antigen-positive cells containing SP or CGRP were found at bilateral sites. These findings indicated that the SP- and CGRP-positive ganglion cells of the trigeminal nerve ganglia innervating the iris or ciliary body, and the NPY-positive ganglion cells of the superior cervical ganglia innervating the iris, ciliary body, and choroid membrane served as the route for the virus spread. These findings also suggested that dopaminergic neurons, such as the TH-positive retinal cells and TH-positive ganglion cells of the superior cervical ganglia, served as the route for virus spread.     

Disease in a dairy herd associated with the introduction and spread of bovine virus diarrhoea virus

In January 1982 an outbreak of diarrhoea among adult dairy cows in a closed herd of approximately 200 milking animals was shown to be caused by the introduction of bovine virus diarrhoea virus (BVDV). Affected animals showed a significant reduction in milk yield. One animal died and four were culled. Eight cows aborted and one weak calf was born. Of 121 calves born that year, 26 died, mostly from pneumonia, but five aged from three weeks to five months had enteric lesions of mucosal disease. Subsequent investigations of the whole herd in 1983 and 1984 showed that virus spread among the adults was slow and that BVDV continued to make a major contribution to calf losses. Again the greatest cause of loss was suppurative or fibrinous pneumonia. Overall, BVDV was isolated from 36 animals. Isolation of virus from a wide range of tissues of individual animals confirmed that they were viraemic at death. Viruses from calves dying of pneumonia and from aborted fetuses were non-cytopathic in tissue culture. Isolates showing varying degrees of cytopathogenicity were obtained only from tissues of one calf with a congenital neurological defect and the seven animals with enteric lesions consistent with a diagnosis of mucosal disease. Blood from all 89 BVDV antibody-free animals older than three months was tested for the presence of BVDV. Altogether, 12 calves were identified as persistently viraemic and all were apparently healthy when bled. Only two matured normally, four grew poorly and six died.(ABSTRACT TRUNCATED AT 250 WORDS)